1. Field of the Invention
This invention relates to a solar heat collector for a hot water supply, solar heat air conditioning systems and the like.
2. Description of the Prior Art
Heretofore, there have been proposed various types of solar heat collectors for the hot water supply, solar heat air conditioning systems and the like.
FIG. 1 is an explanatory view illustrating a solar heat collector 1 widely used. This solar heat collector 1 comprises: an absorber plate 2 for converting the solar rays into thermal energy to transmit the thermal energy to a heat transfer medium such as water; a heat transfer medium flow path 3 formed in the absorber plate 2; a transparent sheet 4 made of glass or the like for preventing the convection heat loss from the absorber plate 2 and protecting the absorber plate 2 against the contamination and damages caused by the external factors; a heat insulating material 5 for preventing the heat loss through the rear surface of the solar heat collector; and an outer box 6 for protecting the absorber plate 2 and the insulating material 5, totally covering the solar heat collector in cooperation with the transparent sheet 4.
The collector performance of the abovedescribed solar heat collector is improved by suppressing the convection radiation and conduction losses from the absorber. As the methods of suppressing the heat losses described above, heretofore, there have been adopted such methods that the surface of the absorber plate 2 is subjected to a selective absorption surface treatment for suppressing the radiation heat loss, a convection preventive structure such as a honeycomb transparent heat trap for suppressing the convection heat loss is provided between the absorber plate 2 and the transparent sheet 4.
FIGS. 2 and 3 are explanatory views showing the conventional solar heat collectors 10 and 20 having convection preventive structures, respectively. In the solar heat collector 10 shown in FIG. 2, the honeycomb heat trap 11 is provided between an absorber plate 2 and a transparent sheet 4 in a manner to contact both the absorber plate 2 and the transparent sheet 4. Furthermore, in the solar heat collector 20 shown in FIG. 3, a honeycomb heat trap 21 is provided between the absorber plate 2 and the transparent sheet 4 in a manner to contact the absorber plate 2, but not to contact the transparent sheet 4.
However, in the abovedescribed conventional solar heat collectors 10 and 20, the honeycomb heat traps 11 and 21 are provided in a manner to contact the absorber plate 2, whereby the heat traps are heated to radiate large quantities of infrared rays, with the result that the radiation heat losses from the honeycomb heat traps 11 and 21 to the transparent sheets 4 increase to a high extent irrespective of that the absorber plates 2 have been subjected to the selective absorption surface treatment for suppressing the radiation heat losses on the surfaces of the absorber plates 2. Furthermore, in the conventional solar heat collector 10 and 20, the honeycomb heat traps 11 and 21, being disposed in contact with the absorber plates heated to a high temperature, are required to have a durability for temperature up to200.degree.-250.degree. C. Additionally, as shown in FIG. 2, in the solar heat collector 10, in the case of the honeycomb heat trap 11 being located in close contact with the absorber plate 2 and the transparent sheet 4, it presents a disadvantage that the honeycomb heat trap 11 may be broken down when the transparent sheet 4 is deformed due to an external force such as wind pressure, snow load or the like.